PrEP trial for adolescents: a promising step forward for HIV prevention

20 September 2017

A US trial among 15 to 17 year-old men who have sex with men (MSM) suggests this group stands to benefit hugely should pre-exposure prophylaxis (PrEP) be approved – and supported – for this age group. 

teenage boys smiling

Biomedical advances in HIV prevention have taken a huge leap forward in recent years, with pre-exposure prophylaxis (PrEP) now approved for use by a growing number of countries for those aged 18 and over. 

Yet despite AIDS being the leading cause of death for adolescents in sub-Saharan Africa, and the second leading cause of death for adolescents worldwide, under-18s are generally excluded from PrEP trials. As a result of limited data on the efficacy, acceptability and safety of PrEP among this age group – and despite the clear need – the approval of PrEP for under-18s has stalled. 

In the USA, the need to address PrEP use among younger MSM couldn’t be starker. Adolescent MSM are the group most likely to become HIV positive in the USA. Young black MSM are particularly affected, with 40% likely to acquire HIV by the time they are 40 unless prevention efforts improve. 

Project PrEPare, by the Adolescent Trials Network, has sought to address this gap with the first open label study to examine the effectiveness of PrEP among under-18 MSM. The US-based trial studied the effectiveness of PrEP among 78 high-risk 15-to-17 year-old MSM over a 48-week period between 2013 and 2014.  

Despite its relatively small sample size, the study had a diverse ethnic mix: two participants (3%) were Asian/Pacific Islander, 23 (29%) were black/African American, 11 (14%) were white, 16 (21%) were white Hispanic, and 26 (33%) had another ethnic identity. Although most participants lived with their families, they were not required to gain parental consent to take part in the trial.  

During the study, approximately half achieved the protective drug levels needed for PrEP to be effective, although adherence waned as the trial advanced. Interestingly, all participants were able to take at least two doses per week, indicating they were attempting to adhere, albeit with less frequency than was needed.  

Particularly revealing is the fact that the rate of HIV-infection among those who did not effectively adhere to PrEP was almost double the rate of infection among 18 to 22-year-old MSM involved in a parallel PrEP study. This highlights the importance of understanding what may prevent younger adolescent MSM from effectively adhering to PrEP, of which this trial provides crucial insight.  

The most commonly reported reasons for missing PrEP doses during the trial were being away from home, being too busy, forgetting, and changes in routine. The authors also identify the striking drop in PrEP adherence once participants began quarterly, rather than more frequent, check ups.  

These findings clearly indicate how essential age-appropriate adherence support will be should countries begin to approve PrEP for use among younger adolescents. Indeed, the study’s authors suggest a number of interventions that should be pursued including the use of mobile technology for medication reminders and supportive check-ins, alongside adherence-buddy schemes and support clubs. The study also suggests the development and testing of longer-acting types of PrEP, which do not require pills to be taken daily, as an important area for clinical research. 

An important insight from the trial comes from the finding that those who failed to effectively adhere to PrEP were more likely to endorse the statement “I worry others will see me taking pills and think that I am HIV-positive”. Here, we see how stigma ultimately limits access to PrEP for those who may benefit from it the most, a structural area that any future adolescent PrEP programmes must address if they are to be effective. 

As the study’s authors rightly assert, further research is needed to explore adolescents’ knowledge of PrEP and their perceptions of risk. Clinicians also require guidance and skills to support administering PrEP to adolescents, including how to navigate insurance requirements, incorporate PrEP into adolescent-centred care, and address structural barriers such as parental consent.  

What is clear from this study is that under-18s most at risk to HIV can be successfully involved in biomedical trials. Without further projects such as this one, advances in the HIV response will continue to leave younger people behind, and the barriers they face to accessing life-saving tools such as PrEP could become insurmountable. 

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Written by Hester Phillips